Fluid imbalance in critically ill patients is associated with greater morbidity and mortality, so the hydration status of patients in intensive care units (ICU) should be monitored. Researchers in Italy tested the association between hydration status measured using bioimpedance vector analysis (BIVA) and mortality in 64 adult patients admitted to the ICU at a single hospital.

BIVA at admission was used to classify patients according to hydration status into three groups: normohydration or dehydration, mild hyperhydration, and moderate or severe hyperhydration. BIVA was repeated daily until death (15 cases) or day 5 in the ICU (49 cases), for a total of 280 measurements. Over 70% of patients had fluid overload at admission; a similar percentage of fluid overload was observed on day 5. The 60-day mortality was 31.2% (20 cases), without differences between the groups.

Statistical analysis showed a significant association between mortality and both the mean and the maximum hydration status observed over 5 days in ICU, with nonsurvivors having had more severe hyperhydration. The authors commented that “measurement of the hydration status through BIVA can constitute an additional methodology to achieve correct monitoring of a patient’s fluid balance. It may also provide insight into the patient’s ideal weight, hence driving a more appropriate therapy management by ultrafiltration and diuretics in critically ill patients. This can ensure an adequate circulating blood volume and prevent complications during fluid removal.”